"so are you" versus "so do you"

[rowan]

I recently watched a tv drama. There's one dialogue that I don't quite understand. The character said, "She needs help, so are you."

I just want to ask why she didn't say "She needs help, so do you."

I'll be glad if anyone can help.

[Alan]

Hi Rowan,

It sounds to me that you may not have heard exactly what the character said. On the face of it, as you write, it should be: She needs help, so do you. Possibly the sentence could have continued like this: She needs help so, are you going to get her some help/going to do something about it?

A
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